Abstract: Urban complex has the characteristics of large and complicated structures and diverse social functions. The traffic flow lines within complex are crucial for urgent evacuation and rescue after seismic events. Existing researches have combined the basic behavioral simulation methods of personnel to simulate the post-earthquake evacuation process by analyzing the damage of structural and non-structural components and setting up obstacles accordingly. They have not fully considered the changes in the evacuation environment of buildings after the earthquake, and neglected the difference in evacuation speed under different damage states of building components. And there is a lack of evaluation indicators to quantify the post-earthquake traffic flow lines function of complex buildings. This paper proposes a quantitative method for evaluating the functionality loss of traffic flow lines within complex buildings following seismic events. Based on the fragility analysis of components, the method models the reduction in maximum evacuation speed considering the change of occupants’ motions under different damage states of non-structural components. The scenarios for building evacuation are established by analyzing the maximum speeds and behavior delay of occupants at different spatial locations within the post-earthquake complex. It constructs the quantitative indicator of the functionality loss of traffic flow lines. Finally, the process is established accounting for uncertainties such as component damage to evaluate the functionality loss of traffic flow lines by expanding the Engineering Demand Parameters. The process is applied to a specific urban complex, demonstrating the loss of the traffic flow lines on each floor and in different areas within post-earthquake complex. It also identifies the weak floors that significantly influence the evacuation. These findings provide valuable insights for evaluating the functionality loss of the post-earthquake urban complex.